Fuel additives

ABSTRACT

N-hydrocarbyl-N-heterocyclic polyamines are found to display detergency in the internal combustion engine when present in fuels to the extent of 10-4,000 ppm. The nitrogenous composition is composed of a hydrocarbyl group bonded to a nitrogen atom, which is itself attached to a heterocyclic polyamine. the hydrocarbyl substituent contains from 30 to about 300 carbon atoms.

United States Patent [191 Honnen [4 Feb.4,1975

[ FUEL ADDITIVES [75] Inventor: Lewis R. Honnen, Petaluma, Calif.

[73] Assignee: Chevron Research Company, San

Francisco, Calif.

[22] Filed: Jan. 7, 1974 [21] Appl. No.: 431,457

3,275,554 9/1966 Wagenaar 252/50 12/1968 Anzenberger 44/63 4/1971 l-lonnen et al. 44/72 Primary Examiner-Daniel E. Wyman Assistant Examiner-Y. H. Smith Attorney, Agent, or FirmG. F. Magdeburger; C. J. Tonkin; S. R. La Paglia [57] ABSTRACT N-hydrocarbyl-N-heterocyclic polyamines are found to display detergency in the internal combustion engine when present in fuels to the extent of 10-4,000 ppm. The nitrogenous composition is composed of a hydrocarbyl group bonded to a nitrogen atom, which is itself attached to a heterocyclic polyamine. the hydrocarbyl substituent contains from 30 to about 300 carbon atoms.

14 Claims, N0 Drawings FUEL ADDITIVES BACKGROUND OF THE INVENTION Field of the Invention Modern research into fuel compositions for the internal combustion engine has for its principal goal the promotion of longer engine life with less maintenance and better performance. This goal is partly achieved by the use of fuel additives which cleanse the carburetor and intake valves and help to maintain their cleanliness. I-Ionnen and Anderson in U.S. Pat. No. 3,438,757 disclosed the use for this purpose of certain hydrocarbyl polyamines as fuel additives, including alkylene monopiperazine polyamines. U.S. Pat. No. 3,275,554 and British Pat. No. 1,004,41 I teach that the N-alkylated hydrocarbyl polyamine or cyclic polyamine can find use as a lubricating oil additives. U.S. Pat. Nos. 3,700,598 and 3,753,670 disclose the use of certain hydrocarbyl polyamines as fuel additives and U.S. Pat. No. 3,717,447 discloses a nitrogen heterocyclic substituted carbamate as a carburetor detergent.

SUMMARY OF THE INVENTION A fuel additive is provided for liquid fuel compositions and fuel concentrates which is effective in intake valve deposit control and maintaining carburetor cleanliness. The additive consists of certain fuel-soluble N-hydrocarbyl-N-heterocyclic polyamines, other than piperazine. The N-heterocyclic polyamine contains from 2 to about 6 nitrogen atoms and from 3 to about 30 carbon atoms and the hydrocarbyl substituent contains from 30 to about 300 carbon atoms. The additive is present in the liquid hydrocarbon fuel in amounts of from 10 ppm to about 4,000 ppm and in fuel concentrates having a suitable solvent for admixture with the liquid fuel in amounts of from 10 to 70 weight percent.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS A fuel additive, and fuel composition containing a major amount of a liquid hydrocarbon fuel and lO-4,000 ppm of said additive, wherein the additive is a nitrogenous composition consisting of a N-hydrocarbyl'N-heterocyclic polyamine, other than piperazine. The two parts of the nitrogenous composition consist of a N-heterocyclic polyamine and a high molecular weight hydrocarbyl substituent. The N- heterocyclic polyamine consists of a single 3-6 membered ring, or 2-5 such rings, each ring containing at least one nitrogen atom. A ring may be alkyl-, hydroxyor amino-substituted such that the total number of nitrogens in the composition is at least two. Since at least two nitrogen atoms are present in the composition, including ring-nitrogen, the composition is termed a polyamine.

The fuel additives of the present invention are preferred and chosen for specific fuel compositions with a view to the required fuel characteristics and the operating conditions of the engine. An additive is preferred if it passes the harm tests measuring water tolerance, fil ter plugging, particulate suspension, rust and corrosion, additive compatibility, toxicity, octane depreciation, bearing corrosion, anti-icing, lubricating oil compatibility, fuel system material compatibility or paint deterioration.

Particular preferred additives are selected for compatibility with unleaded fuel (i.e., fuel containing less 2 than 0.1 gm of lead per gallon), inhibition of preignition, inhibition of crankcase sludge following normal blow-by, combustion chamber deposit control, anti-rusting, or dispersancy.

The most preferred additives of the present invention would be those which effect a reduction or control of hydrocarbon or carbon monoxide emissions, display carburetor detergency, intake valve deposit control, or are compatible and beneficial to an exhaust gas recirculation system (EGR) or early fuel evaporation system (EFE) cleanliness.

HYDROCARBYL SUBSTITUENT Hydrocarbyl, as used in this invention, denotes an organic radical composed of carbon and hydrogen which may be aliphatic, alicyclic, aromatic or combinations thereof, e.g., aralkyl. Elements other than carbon and hydrogen, such as oxygen, or chlorine, form a minor, insubstantial, sometimes adventitious, component of the hydrocarbyl group. Preferably, the hydrocarbyl group will be relatively free of aliphatic unsaturation, i.e., ethylenic and acetylenic, particularly acetylenic unsaturation.

The hydrocarbyl group in the N-hydrocarbyl-N- heterocyclic polyamine, other than alkylene monopiperazine, will contain at least 30 carbon atoms, less than about 400 carbon atoms and preferably 300 or less. The hydrocarbyl group is preferably of 50-300 carbon atoms and most preferably has in excess of 65 carbon atoms. The hydrocarbyl groups are preferably aliphatic, having preferably from 0 to 2 sites of ethylenic unsaturation and most preferably from 0 to 1 such site. l-Iydrocarbyl groups derived from a polyolefin, itself derived from olefins (normally l-olefins) of from 2 to 6 carbon atoms with the proviso that ethylene is copolymerized with a higher olefin i.e., ethylene is copolymerized with an olefin of at least 3 carbon atoms, or from a high molecular weight petroleum-derived hydrocarbon, are preferred and of these polyisobutene is most preferred. Illustrative sources for the high molecular weight hydrocarbyl substituents are: petroleum mineral oils, and polyolefins, such as naphthenic bright stocks, polypropylene, polyisobutylene, poly-l-butene, copolymers of ethylene and propylene, polyl -pentene, poly-4-methyl-l-pentene, poly-l-hexene, poly-3- methyl butene, etc.

The N-hydrocarboyl-N-heterocyclic polyamine other than piperazine, is usually derived from the reaction of the halogenated hydrocarbon with the N-heterocyclic polyamine in the desired mcl proportions, usually from about I24 to about 2:l. The hydrocarbyl halide is prepared from the hydrocarbon by halogenation, ionically or free radically, by addition or allylic substitution. The hydrocarbon may be prepared by polymerization of olefins of from 2 to 6 carbon atoms to produce a polyolefin of the desired molecular weight. The method of halogenation and subsequent reaction of the hydrocarbyl halide with a polyamine has been previously described in U.S. Pat. Nos. 3,565,804 and 3,671 ,51 l, and is typical of the synthesis of the compounds of the present invention.

To provide for reaction with the hydrocarbyl halide to form the additives of the present invention, it is required that the N-heterocyclic polyamine before reac tion with the hydrocarbyl halide contain at least I primary or secondary amino nitrogen atom. The reaction with halogenated hydrocarbon is not believed to produce appreciable amounts of dior poly-substituted hydrocarbon, rather, it is believed that each hydrocarbon group is monovalently substituted to a particular nitrogen atom of the nitrogenous substrate.

The hydrocarbyl substituents in the N-hydrocarbyl- N-heterocyclic polyamine can be found at any nitrogen atom which is capable of receiving it. The nitrogen atoms, in general, are inequivalent by symmetry so that the substituted compounds which find use in this invention are mixtures of monoand polyhydrocarbyl substituted compounds with hydrocarbyl groups substituted at various equivalent and inequivalent nitrogen atoms and could be denoted N-hydrocarbyl, N,N- dihydrocarbyl, etc. The molecular weights used herein are number average molecular weights. To obtain an average carbon number from the average molecular weight of the hydrocarbon, divide by 14, which represents the weight of CH2.

In many instances, a single compound will not be used as a reactant in the preparation of the compositions of this invention. For example, commercially available polyamines are sometimes mixtures in which one or two compounds will predominate and the average composition or molecular weight is indicated. Similarly, the average molecular weight of carbon number reported for the hydrocarbyl substituents is usually an average value of a rather sharply peaked distribution. Also, as stated previously, when the nitrogens are inequivalent, substitution of the various groups on different nitrogens provides different isomers as does isomeric branching of the polyamines. The number of hydrocarbon substituents need not be a whole number when averaged over a total composition, since generally, a mixture will be obtained containing mono, dior higher substituted. molecules averaging out to a fractional or whole number.

N-HETEROCYCLIC POLYAMINE A comprehensive exposition of the chemistry, method of preparation and literature of these nitrogenous materials is found in Sidgwicks The Organic Chemistry of Nitrogen", Clarendon Press, Oxford, 1966; and in Nollers Chemistry Organic Compounds, Saunders, Philadelphia, 2nd Ed., 1957. The N-heterocyclic polyamine consists ofa single 3-6 membered ring, or 2-5 such rings, each containing at least one nitrogen atom. The ring may be alkyl, hydroxy or amino substituted such that the total number of nitrogen atoms in the composition is at least 2. Typical N- heterocyclic ring systems include aziridine, azetidine, azolidine, azole, azine, pyridine, pyrazine, pyrrole, imidazole, pyrimidine, piperidine, pyrazolidine, morpholine, imidazolidine, etc.

The cyclic polyamine finding use within the scope of the invention is a N-heterocyclic compound, other than piperazine, having at least 1 nitrogen atom and at least 2 carbon atoms in the heterocyclic ring, but containing in total at least 2 or more nitrogen atoms. It may be mono-cyclic or polycyclic, alicyclic or aromatic, and normally contains 5- or 6-membered rings. The cyclic polyamine contains from 2 to about 12 nitrogen atoms, preferably from 2 to about 6 nitrogen atoms, and from 2 to about 50, preferably from 2 to about 30, carbon atoms and is illustrated by N-aminopropyl morpholine, cyclotrimethylenetriamine (hydrotriazine), triaminocyclotrimethylenetriamine (hydromelamine), aminoethyleneaziridine, aminoethyleneazetidine, aminoethylenepyrrolidine, aminoethylenepiperidine, 2,6- diaminopyridine, and cyclohexamethylenetetramine. The properties, methods of preparation and further references for cyclic polyamine can be found in Kirk- Othmer, The Encyclopedia of Chemical Technology, Vol. 2, pp. 99-1 16 (also see Sidgwick, Chapter 29).

The N-heterocyclic polyamine imparts desirable and useful properties to the high molecular weight hydrocarbyl substituent as a fuel additive; e.g., properties such as basicity, rust and corrosion inhibition, thermal or oxidative stability of the fuel composition and detergency. However, these properties of the N-heterocyclic polyamine are by no means exclusive, since viewed in another way, the high molecuar weight hydrocarbyl substituent is found to increase the effectiveness of the N-heterocyclic polyamine as a detergent fuel additive without diminishing its other desirable properties. It is a preferred embodiment of the present invention that these additives be used in combination with other fuel additives to achieve maximum performance at minimum cost.

COMPOSITIONS Depending upon the particular application of the additive of this invention, its synthesis may be carried out in the medium in which it will ultimately find use, and it may be formed in concentrations which provide a concentrate of the additive. Thus, the final composition may be in a form to be used directly upon dilution in fuels or fuel concentrates. The additive of this invention is generally employed in hydrocarbon liquid fuels. It may be formulated as a fuel concentrate using a suitable solvent, preferably an aromatic hydrocarbon solvent such as benzene, toluene, xylene or other low boiling aromatic thinner. Aliphatic alcohols of about 3-8 carbon atoms such as isopropanol, isobutanol, nbutanol, 2-ethyl hexanol and the like, also in combination with hydrocarbon solvents, are suitable for use with the additive. Other polymeric materials may also be used in conjunction with the additive of this invention, e.g., polypropylene, polyoxyalkylene glycol.

The liquid hydrocarbon fuels of the present invention encompass fuels boiling in the gasoline and diesel oil range, e.g., having ASTM D-86 90% points from about 200F (about 90C) to about 700F (about 370C) and generally boiling from about 100F (about 37C) to about 750F (400C).

In the fuel, the concentration of the additive will generally be at least 10 ppm and usually not more than 4,000 ppm, more usually in the range of from about 50 to 1,500 ppm. ln fuel concentrates, the additives will range from about l-90 weight percent, more usually from about 10 to weight percent and generally not exceeding weight percent. In gasoline fuels, other fuel additives may also be included such as antiknock agents, e.g., tetramethyl lead, tetraethyl lead; also included may be lead scavengers such as arylhalides, e.g., dichlorobenzene or alkylhalides, e.g., ethylene dibromide; and antioxidants such as alkylated phenols or aromatic amines. A nonvolatile lubricating mineral oil, e.g., petroleum spray oil, particularly a refined paraffinic or naphthenic lubricating oil, having a viscosity at F of 80-2000 SUS is a suitable oil-additive for the gasoline composition when used with the additives of the present invention. Polymeric materials as mentioned above, such as polyolefms and glycols, such as polypropylene glycol, can also be used. These materials are believed to act as a carrier for the additive and assist in removing and preventing deposits. They are em- EXAMPLE 1 To a 1,000 ml flask equipped with thermometer and reflux condenser was added 70.0 grams of tetrahydrostriazine, molecular weight 132, as a 50 percent solution in water, (about 0.266 mols), 200 grams of polybutenyl chloride of average molecular weight about 1,400, and 300 ml of methyI-Z-pentanol. The mixture was refluxed at 99C for 4 hours, whereupon the temperature was raised to 135C and held for 6 hours. The mixture was cooled, diluted with hexane, alcohol and washed until neutral. The product was stripped of solvent and analyzed. 202 grams of product were obtained having 1.33% N, 1.25% Cl, and an average molecular weight about 1,865, indicating the product was substantially monopolyisobutenyl-tetra-hydro-s-triazine.

EXAMPLE 2 500 grams of a polyisobutenyl chloride of about 950 molecular weight was mixed with 400 grams of aminopropyl morpholine at about 150C. The temperature was maintained at about 150C for about 3 hours. The crude product was worked up as in the previous example and found to contain 2.27% N.

EXAM PLE 3 Diaminopyridine (90 grams, about 0.83 mols) was mixed with 560 grams (about 0.4 mols) of polyisobutenyl chloride of about 1,400 molecular weight. In 400 ml of xylene and 500 ml of 4-methyl-2-pentanol the mixture was heated to reflux (130C) and held for about 6 hours in the temperature range of 130l50C. The product was cooled, diluted with hexane, and washed with three portions of 60% water, 30% alcohol and 10% isobutanol. The product (313 grams) was stripped of solvent and found to contain 1.68% N.

EXAMPLE 4 Cyclohexamethylenetetramine (112 grams, about 0.8 mols) was mixed with 200 grams (about 0.2 mols) of polyisobutenyl chloride of about 1,000 molecular weight in 200 ml of xylene, 250 ml of dimethylformamide, 100 ml of 4-methyl-2-pentanol, and 80 m1 of water. The mixture was heated to reflux with stirring, 105C. Two phases formed with much undissolved solid. The mixture was refluxed for a total of about 14 hours, and worked up as in previous examples to obtain 173 grams of product of about 0.68% N and 1.06% Cl.

EXAMPLE 5 The methyl imidazoline of diethylene triamine (50 grams, about 0.39 mols) was mixed with 200 grams (about 0.14 mols) of polyisobutenyl chloride of about 1,400 average molecular weight in 100 ml of xylene. The mixture was heated to reflux for 5 hours, cooled and diluted with hexane. The product was washed with aqueous alcoholic solution and stripped of solvents to yield 183 grams of product, 1.48% N.

EVALUATION The fuel additives were evaluated, among other attributes, for their ability to maintain intake system cleanliness ir'ithe lO-hourlntake Valve Deposit Test. The engine used in thistest isa Wauk'esha vASTM-CFR single-cylinder engine. Upon completion of the test the intake valve is removed, washed with hexane and weighed. The deposits are then removed with a wire brush and the valve re-weighed. The difference between the two weights is the weight of deposit. Operating conditions include an engine speed of 1,800 rpm, a water temperature of 212F C), a manifold vacuum of 15 inches of Hg, a fuel-air mixture temperature of F (52C). an air-fuel ratio of 14, and intake spark timing 15 BTC. All fuel samples, including the hydrocarbon base fuel, contain 1,000 ppm of a 1,700 SUS at 100F (38C) neutral petroleum oil. The additive concentration is 250 ppm in the base fuel which is predominantly a Chevron gasoline. Fuel compositions are evaluated by comparing the number of mg of hexane washed deposits produced by the following fuel additive compositions with the 139 mg of hexane washed deposits produced by the base fuel sample.

TABLE I lO-Hour CFR Intake Valve Test Additive Intake Valve Deposits polyisobutenyl-N-amino Polyisobutenyl group of about 950 ave. mul. wt. 2 Pnlyisobutcnyl group of about 1,400 ave. mol. wt.

The data of Table 1 illustrate the effectiveness of the fuel additives of the present invention in controlling intake valve deposits.

1 claim:

1. A fuel composition comprising a major amount of a liquid hydrocarbon fuel and from 10 ppm to 4,000 ppm of a N-hydrocarbyl-N-heterocyclic polyamine, other than piperazine, wherein said N-heterocyclic polyamine contains from 2 to about 6 nitrogen atoms and from 2 to about 30 carbon atoms, and said hydrocarbyl substituent contains from 30 to about 300 carbon atoms.

2. A fuel composition according to claim 1 wherein said N-heterocyclic polyamine contains a sixmembered ring.

3. A fuel composition according to claim 1 wherein said N-heterocyclic polyamine contains a fivemembered ring.

4. A fuel composition according to claim 1 wherein said hydrocarbyl substituent is a polyolefin, derived from C2C6 olefins, with the proviso that ethylene is copolymerized with a higher olefin.

5. A fuel composition according to claim 4, wherein said polyolefin is polybutene or polypropylene.

6. A fuel composition according to claim 2 wherein said N-heterocyclic polyamine is an amino-morpholine.

7. A fuel composition according to claim 2 wherein said N-heterocyclic-polyamine is an amino-pyridine.

8. A fuel composition according to claim 2 wherein said N-heterocyclic polyamine is an amino-piperidine.

9. A fuel composition according to claim 2 wherein said N-heterocyclic polyamine is a triazine.

10. A fuel composition according to claim 1 wherein said N-heterocyclic polyamine is cyclohexamethylenetetramine.

11. A fuel composition according to claim 3 wherein said-N-heterocyclic polyamine is an aminoalkylene imidazoline.

' 12. A fuel composition according to claim 3 wherein said N-heterocyclic polyamine is an amino-pyrrolidine.

13. A fuel composition according to claim 1 wherein said N-heterocyclic polyamine is an amino azetidine or 30 to about 300 carbon atoms.'

i l I! 

2. A fuel composition according to claim 1 wherein said N-heterocyclic polyamine contains a six-membered ring.
 3. A fuel composition according to claim 1 wherein said N-heterocyclic polyamine contains a five-membered ring.
 4. A fuel composition according to claim 1 wherein said hydrocarbyl substituent is a polyolefin, derived from C2-C6 olefins, with the proviso that ethylene is copolymerized with a higher olefin.
 5. A fuel composition according to claim 4, wherein said polyolefin is polybutene or polypropylene.
 6. A fuel composition according to claim 2 wherein said N-heterocyclic polyamine is an amino-morpholine.
 7. A fuel composition according to claim 2 wherein said N-heterocyclic polyamine is an amino-pyridine.
 8. A fuel composition according to claim 2 wherein said N-heterocyclic polyamine is an amino-piperidine.
 9. A fuel composition according to claim 2 wherein said N-heterocyclic polyamine is a triazine.
 10. A fuel composition according to claim 1 wherein said N-heterocyclic polyamine is cyclohexamethylenetetramine.
 11. A fuel composition according to claim 3 wherein said N-heterocyclic polyamine is an aminoalkylene imidazoline.
 12. A fuel composition according to claim 3 wherein said N-heterocyclic polyamine is an amino-pyrrolidine.
 13. A fuel composition according to claim 1 wherein said N-heterocyclic polyamine is an amino-azetidine or an amino-aziridine.
 14. A fuel concentrate composition having a suitable solvent for admixture with a hydrocarbon fuel and from 10 to 70 weight percent of a N-hydrocarbyl-N-heterocyclic polyamine, other than piperazine, wherein said N-heterocyclic polyamine contains from 2 to aobut 6 nitrogen atoms and from 2 to about 30 carbon atoms, and said hydrocarbyl substituent contains from 30 to about 300 carbon atoms. 